Selector for telephone installations



March 9, 1937. A. WIRTH SELECTOR FOR TELEPHONE INSTALLATIONS 2Sheets-Sheet 1 Filed Aug. 15, 1935 Off Inventor W ZZ/M y I flitor'neysMarch 9, 1937. A. WIRTH 2,073,087

SELECTOR FOR TELEPHONE INSTALLATIONS Filed Aug. 13, 1935 2 Sheets-Sheet2 Patented Mar. 9, 1937 UNlTED STATES SELECTOR FOR TELEPHONEINSTALLATIONS Alexander Wirth, Frankfort-on-the-Main, GermanyApplication August 13, 1935, Serial No. 36,005 In Germany January 23,1934 11 Claims.

This invention relates to selectors for telephone systems and moreparticularly to means for moving or lifting selector switch members backinto normal inoperative position for reiunctioning.

Selectors are known in which energy for effecting the movement of theswitch members onto a particular contact is stored up and released. Whenthe selector is no longer in use, these switch members must be returnedagain to their normal position. The energy required for setting theswitch member may be stored during this return movement. This may beeffected by tensioning a spring. If the switch member moves into itscontact-making position under the in- 19 fluence of gravity, it has tobe raised into the starting position in a, or during the, returnmovement. This return movement can be controlled by various means, forexample by an electromagnetic stepping switch, or by pneumatic ormechanical means.

According to the invention, the switch member is returned raised. intothe normal position by rotary carrier means which are provided atintervals with means for moving the switch memher.

In order that the invention may be thoroughly understood and be morereadily carried into effect, some forms of construction in accordancetherewith will now be described with reference to the accompanyingdrawings, wherein:-

Figure 1 is a diagrammatic illustration of a form of conveyor inaccordance with the invention applied to the lower end of a switchmember also shown diagrammatically;

Figure 2 illustrates the operation of a modified form of a detail shownin Figure 1;

Figures 3 to 6 show various modified forms of construction of theconveyor; Figure 5a. being a plan view of main Fig. 5;

Figure '7 illustrates the selector, in somewhat fuller detail, in theinoperative position; and

Figure 8 is a plan view of an arrangement according to Figure l.

45 The selectors and the switch members contemplated herein are of thegeneral form and character shown and described for example in the U. S.patent to Merk, No. 1,849,986 dated March 15, 1932, but are not hereillustrated in 50 detail because it is not material or essential to fullunderstanding, and only those parts of the switch members which are orare intended to be, in engagement with the carrier means are shown sincethat is sufficient for the instant purpose. It

55 is assumed that the switch members are to be raised by the carriermeans, as is frequently necessary in the case of the switch members ofmultiple brush selectors.

The conveyor in the example illustrated in Figure 1 consists of anendless band b, which is provided with driving members m for moving theswitch members, and is driven in the direction indicated by the arrowsby the wheels re and T'LL mounted on the shafts wo, um. The selectorswitch member 2, to be moved, has a pawl 76 which is shown in Figure 1in four difierent positions A, B, C, D which it assumes during onelifting cycle. This pawl is mounted to turn about a pivot a, and is heldby gravity or by means of a spring (not illustrated) in the normalposition B.

During the setting of the selector and while it remains set, the pawl k:remains in the normal position. When the selector becomes free, theswitch member 2 moves downward until the pawl k abuts against the fixedstop 8 and is thus brought into the position D. This brings the pawl isinto the path of movement of the driving members m, so that the pawl kand, therefore, the switch member a move together with that member mwhich makes contact with the pawl 70.

In order to avoid the shock which might occur should the selectorconnected to the member 2 be suddenly set in movement, the pawl k isfirst raised by the member m without causing the switch member 2 to risewith it at the full speed of the band b. For this purpose, the pawl 10has a tail or lug c which abuts against the stop s, so that the switchmember 2 will be slowly moved as the point of abutment of the tail 2;against the stop s and of the member m on the pawl It changes, and it isonly when the pawl 7c has reached the stop 1 in position C that theswitch member a is moved at the full speed of the band 17.

During this first part of the driving cycle, the distance of the pointof abutment of the pawl 70 on the member m from the pivot a is graduallyreduced so that the speed at which the switch member 2 rises graduallyincreases correspondingly. The upper wheel rd of the conveyor isdisposed so that the member m loses contact with the pawl is when theselector has reached its highest or normal position A, in which theswitch member 2 is held by a pawl is (see Fig. '7). The return movementof the selector is thereupon completed, and the pawl 7c which was incontact with the driving member m, being then released, falls back againinto its normal position B. During the last part of the return movementof the selector switch member 2, the speed at which said member islifted is reduced because the driving member m follows the periphery ofthe Wheel r0, and the speed of course approaches zero as said drivingmember m nears the point vertically above the shaft 100. Thus the pawlIt can securely engage a notch of the selector switchmember 2, asalready indicated, and hold said member in its normal position, whilethe load on the conveyor is gradually and slowly removed as the pawl itreleases from said driving member m. The stop I is preferablyresiliently mounted so that varieties in the load, such as may occur forexample when the contacts are actuated, are equalized by the spring orother resilient arrangement.

Owing to some mechanical defect, the selector might be damaged if apositive drive of the switch member were always maintained during thereturn movement. Fig. 2 shows an arrangement which will guard againstthis possibility and efiect disconnection of a selector'upon theoccurrence of an overload. This is contrived by means of a specialconstruction of the stop 1. In this instance, said stop 1 consists oftwo leaf springs, a weak spring fl and a stronger spring f2. The springfl holds the pawl 70 in its normal position here represented by M.During the return movement of the selector, the tail 2) of the pawl kpresses against the springs fl and f2. The strength of the spring fl issuch that when the load is normal, the pawl 7c assumes the position N.If the load on the switch member is greater than normal however, thepawl 70 escapes from the member m and after passing through a deadcentreposition 0, is brought by the springs fl and f2 into the position P whenthe member 112. loses contact with the pawl 7c. An electricaldisconnection of the selector may also be eifected simultaneously withthis mechanical disconnection.

The normal or inoperative position of the switch member, or selector,and the means for holding it in this position, ready for operation, isillustrated in Fig. 7. In this view, the switch member a is shown insomewhat fuller detail, having notches formed therein, at one side,something like a rack. Engaging in these notches of the member is a pawlit which is subject to the action of the spring 1.. The pawl 7c carriesthe armature p of a magnet 122. When the magnet m is excitedmomentarily, the pawl k is drawn out of the rack momentarily so as torelease the 'switch member a for operative action by gravity, and ofcourse reengages said member 2 when it is again lifted to the normalstarting position.

The conveyor and switch members described with reference to Fig. 1 (also2 and 7) comprise one of a plurality or series of the same used in afull selector system. They are of course in number or grouping dependingupon the number and arrangement of selectors in the system. Fig. 8 is aplan view representation of a grouping arrangement of such memberslongitudinally in a system of individually adjacent selectors.

A single band I) may be provided for a group of selectors or a separatenarrow band may be provided for each selector. The driving members mwhich are provided for each selector are staggered in each setrelatively to another as illustrated diagrammatically in Figure 3, so asto avoid having to accelerate several selectors simultaneously. A numberof driving members m are advantageously fitted on each band bin orderthat the time required for the return movement of the selector may be asshort as possible.

In order that the shafts carrying the conveyor bands 27 may be of smalldiameter and in order that the cost of the arrangement may be reduced,the shafts zoo and um are made discontinuous or in sections as shown inFigure 3, the breaks in the shafts being staggered relatively to eachother. Each line of shafting thus comprises a number of coaxial shaftparts or sections, the power being transmitted from a section in oneline of shafting to its neighbour through a section in the other line ofshafting. The bands Z) themselves thus serve as couplings and no specialcouplings have to be provided.

If the selectors are fitted on both the front and back of selectorframes and two resetting conveyors are used as represented in Fig. 4,the upper shafts 100 or the lower shafts wu of the two conveyors can becoupled together at several places by toothed wheels (not shown) so thatif one overlappingband on one side of the frame is out of action, thefollowing groups will be driven through the agency of these toothedwheels on the opposite side.

The arrangement of Figure 4 can be simplified for example in the mannerindicated in Figure 5, in which only two shafts zoo and um altogetherare provided, these, however, being rotatable in opposite directions asindicated by the arrows. In this case, the upper wheels T0 of the bandsserving the front of the selectors are rigidly connected to the uppershaft wo, while the corresponding lower wheels m are mounted freely onthe shaft wu. correspondingly, the wheels m serving the back of theselectors are rigidly connected to the shaft um and the wheels m areloose on the upper shaft we. Figure 5a represents a plan view of thisarrangement. In the latter, 2 designates the switch members of twoselectors disposed at one side of the selector frame, and e designatesthe switch members of two selectors disposed on the other side of saidframe.

The resetting device is driven by a motor, and one motor can be providedfor each frame or for a group of frames (see Figure 6). Each motor M1,M2 is provided with a transmission Gtr, set for the desired speed ofrotation and connected to the driven shafts (20 20 through free wheeldevices Fr. This arrangement enables a number of driving units eachprovided with a motor to be coupled directly, the result being that, onfailure of one of the motors, the corresponding driving group can bedriven from the motor of the second group.

The driving motor can at the same time be used for controlling purposesand for the direct or indirect production of the necessary signalcurrent, charging current and soforth, or for other purposes.

I claim:

1. A selector for telephone installations, comprising a switch memberadapted to be set under the influence of a stored force, and rotaryconveying means adapted to act upon and move said switch member backinto its normal position when the selector is no longer busy, the saidrotary conveying means being provided with a series of driving elementseach engageable with means carried by the switch member, and said switchmember having thereon the means engaged by said driving elements movableinto position for such engagement only when said member is in apredetermined position for the return movement and releasing from theengagement when said member has been moved to normal position.

2. A selector for telephone installations, comprising a switch memberfor each selector adapted to be set under the influence of a storedforce, and a constantly operating driving member common to a pluralityof sets of resetting members for resetting the switch member of therespective selectors, each of said sets of resetting memberscorresponding to a selector and each resetting member of a set of suchmembers being adapted to reset the switch member of its correspondingselector into the normal position thereof when said selector is moved ina predetermined position for the return movement.

3. A selector for telephone installations, comprising a switch memberadapted to be set under the influence of a stored force, a couplingmember fixed to said switch member, a stop adapted to deflect saidcoupling member in a predetermined movement limit position of saidswitch member, and rotary conveying means, said rotary conveying meansbeing provided with driving members adapted to engage with said couplingmember when deflected and thereby to return said switch member from saidpredetermined limit position into its normal position.

4. A selector for telephone installations, comprising a switch memberadapted to be set under the influence of a stored force, a couplingmember fixed to said switch member, said coupling member being formed asa two-armed lever with unequal arms, a stop arranged in the path ofmovement of the longer lever arm of said coupling member and adapted todeflect said coupling member when said switch member has reached apredetermined position for starting the return movement, and rotaryconveying means provided with driving members, said driving membersbeing adapted to engage with said deflected coupling member and toreturn said switch member to its normal position.

5. A selector for telephone installations, comprising a switch memberadapted to be set under the influence of a stored force, a couplingmember fixed to said switch member, said coupling member being formed asa two-armed lever with unequal arms, a stop arranged in the path ofmovement of the longer lever arm of said coupling member and adapted todeflect said cou pling member when said switch member has reached apredetermined position for starting the return movement, and rotaryconveying means provided with driving means, said driving means beingadapted to engage with said deflected coupling member and to return saidswitch member to its normal position, and means for disconnecting saidcoupling member from said driving members on the occurrence of anoverload resisting the return movement of said switch member into thenormal position.

6. A selector for telephone installations, comprising a switch memberadapted to be set under the influence of astored force, a movablecoupling member arranged on said switch member,

said coupling member being formed as a twoarmed lever with unequal arms,an oblique stop arranged in a fixed position in the path of movement ofthe longer arm of said coupling memher and adapted to deflect saidcoupling member and thereby arrest the switch member in a predeterminedlower position, a further stop for said coupling member connected tosaid switch member, two rollers, a conveyor band running round saidrollers, said conveyor band being' provided with driving members adaptedto come into engagement with the longer lever arm of said deflectedcoupling member and to return said switch member into its normalposition when said member has reached said pre- 0 determined position.

'7. A selector for telephone installations, comprising a switch memberadapted to be set under the influence of a stored force, a movablecoupling member arranged on said switch member, said coupling memberbeing formed as a twoarmed lever with unequal arms, an oblique stoparranged in a fixed position in the path of movement of the longer armof said coupling member and adapted to deflect said coupling member in apredetermined lower limit position of the switch member, a spring fixedto said switch member and acting on said coupling member, two rollers,one of said rollers being arranged in the neighbourhood of said fixedstop, a conveyor band running over said rollers and provided withdriving members adapted to come into engagement with the longer leverarm of said coupling member when deflected and to thereby return saidswitch member from the predetermined lower limit to its normal positionby displacement of the bearing point on said lever arm as well as toswing said coupling member over by overcoming the tension of the springon the occurrence of an overload resisting the return movement of saidswitch member into the normal position and thus to destroy theengagement with said coupling member.

8. A selector arrangement, comprising a plurality of selectors havingswitch members arranged side by side and adapted to be set under theinfluence of gravity, each of said switch members being provided with acoupling member, a plurality of oblique stops each corresponding to aselector and arranged in the path of movement of said selector andadapted to deflect the coupling member thereof when the switch memberhas reached its lowest position, two shafts arranged one above theother, a number of rollers corresponding to the number of selectors oneach of said shafts, conveyor bands running each over one roller of saidupper and lower shafts, said conveyor bands being provided with drivingmembers adapted to come into engagement with said coupling members whendeflected and to thereby lift said switch members of said selectors intothe normal position, and said driving members of the various conveyorbands being staggered relatively to each other.

9. A selector arrangement, comprising a plurality of selectors withswitch members arranged side by side adapted to be set under theinfluence of gravity, each of said switch members being provided with acoupling member, a plurality of oblique stops each corresponding to aselector and arranged in the path of movement of said selector andadapted to deflect the coupling member thereof when the switch memberhas reached its lowest position, two shafts arranged one above theother, a number of rollers corresponding to the number of selectors oneach of said shafts, conveyor bands running each over one roller of saidupper and lower shafts, said conveyor bands being provided with drivingmeans adapted to come into engagement with said coupling members whendeflected and to thereby lift said switch members of said selectors intothe normal position, said driving members of the various conveyor bandsbeing staggered relatively to each other, and each of said shafts beingsub-divided into a number of sections and carrying a plurality ofrollers, said sections of the upper shaft being staggered relatively tothe sections at the lower shaft, and each conveyor band running over oneroller of one section of the lower shaft and one roller of anothersection of the upper shaft.

10. A selector arrangement, comprising several selectors having switchmembers adapted to be set under the influence of gravity, each of saidswitch members being provided with a coupling member, a plurality ofoblique stops veach corresponding to a selectorand arranged in the pathof movement of said selector and adapted to defiect the coupling memberthereof when the switch member has reached its lowest position, aplurality of groups of driving means, each of said groups containing anupper and a lower shaft with rollers, conveyor bands running round saidrollers, said conveyor bands being provided with driving means adaptedto come into engagement with said coupling members when deflected bysaid stops, a driving motor and free-wheel couplings for connecting theshafts of the individual groups of driving means.

11. A selector arrangement, comprising a plurality of selectors withswitch members arranged side by side adapted to be set under theinfluence of gravity, each of said switch members being provided with acoupling member, a plurality of oblique stops each correspondingarranged in the path of movement of said selector and adapted'to deflectthe coupling member thereof when the switch member has reached itslowest position, two shafts arranged one above the other,

a number of rollers corresponding to the number ALEXANDER WIRTH.

to a selector and

